Need some advice on Ampeg SVG400T...

mennoverbaten · #1 02-02-2011, 06:05 PM

I need some help with my set-up and would greatly appreciate some advice.
I run a Lance Alonzo custom bass with active EMG pickups through an Ampeg SVT400T rack-mount solid state amp, using two cabs; an Ampeg SVT410HLF (4ohms) and a Wizard B410 (8ohms).
The only effect I use continuously is a Boss DS-1 distortion pedal with the level at 50% plugged into the 0dB input.

This setup sometimes causes the amp to go into "thermal shutdown" mode, mostly during live performances, which, as you can imagine, sucks!

I already took the amp out of its SKB rack-case to let the cooling fans do their job, but it still shuts down from time to time.

I am wondering if it's the combo of 8ohm/4ohm cabs, but need to figure out if there might be anything else that can cause this "thermal shutdown".

Please let me know if anyone has any experience with this or where to go to solve this problem. I am going back on the road soon and do not want this to happen again!

Thanks!

Menno.

Hollywars · #2 02-02-2011, 06:06 PM

It probably can't go under 4 ohms, which it is when you use a 4 and 8 ohm cab together.

5string5fingers · #3 02-02-2011, 06:16 PM

Quote:

Originally Posted by Hollywars

It probably can't go under 4 ohms, which it is when you use a 4 and 8 ohm cab together.

This, I would suggest you stop doing that if you like the head.

Darylt · #4 02-02-2011, 06:19 PM

How are you connecting your speakers - are you bridging or bi-amping. If your connecting your cabinets together your load will be in the 2.3 ohm ballpark - could be your problem there - too much load for your amp maybe ...

mennoverbaten · #5 02-02-2011, 06:26 PM

One in each power amp so the minimum load for each speaker is 4ohm. I think that's what the problem is, just need to find out if there is anything else going on.
Probably need to get two 8ohm cabs...

Gravedigger · #6 02-02-2011, 06:35 PM

It's never a good idea to mismatch cab impedance.

waleross · #7 02-02-2011, 06:39 PM

I had one for a year or so and recently sold it to a friend of mine...........Its actually an Ampeg that was out before the SvT4pro, maybe a prototype or such.
It has two channels A & B 200 watts each. I ran my 810E cab without any trouble. Mine was over 20 years old and it was great as a backup. Mixing your 4ohm and 8ohm cab is not the way to go. I hooked it up with a 410E and and 115B for a demo . When I ran the 810 I used one cable from each side of the head. It is a 4ohm head and I would get it checked out before you really test it . Also, I didn't use mine in a rack . This is just my opinion but when you havean old head you have to take it easy................Good luck